On Sun, Jan 15, 2006 at 10:51:56PM +0100, Jens Arnold wrote: > On 15.01.2006, Jacob Erlbeck wrote: > > > This is > > the 'bit reservoir' thing that is only being used for constant > > bitrate streams (it doesn't make much sense for VBR streams). > > It can also be used for VBR, and it makes sense. MPEG audio > frames can only have certain fixed sizes, and the bit reservoir > can be used to further optimise the file size. Let's say we have > 2 blocks of audio (2 frames) which would need 144 kbps frames > at the selected quality. 144 kbps frames don't exist, so the > first frame must be a 160 kbps one. Some bits of it are unused, > and they add to the bit reservoir, which can then be used for a > part of the data of the second frame. The rest then fits in a > 128 kbps frame. > > The MAS3587F does this, in rockbox it can optionally be > deactivated.
Thank you for correcting that nonsense above I wrote. Jacob
